To prevent leakage, in a common electronic-paper (E-paper) display apparatus, each of the pixel structures on a thin film transistor (TFT) array substrate commonly includes two series-coupled TFTs.
FIG. 1 is a schematic view of a conventional pixel structure including two series-connected TFTs. As shown in FIG. 1, the pixel structure includes a first TFT 110 and a second TFT 120 connected in series. The first TFT 110 includes a first gate 112, a first source 114, a first drain 116 and a first semiconductor pattern 118, and the first gate 112, the first source 114, the first drain 116 and the first semiconductor pattern 118 respectively have a rectangular shape. Specifically, the first source 114 and the first drain 116 respectively partially overlap the first gate 112, the first semiconductor pattern 118 is disposed above the first gate 112, and two partial areas of the first semiconductor pattern 118 respectively are covered by the first source 114 and the first drain 116.
The second TFT 120 includes a second gate 122, a second source 124, a second drain 126 and a second semiconductor pattern 128, and the second gate 122, the second source 124, the second drain 126 and the second semiconductor pattern 128 respectively have a rectangular shape. Specifically, the second source 124 and the second drain 126 respectively partially overlap the second gate 122, the second semiconductor pattern 128 is disposed above the second gate 122, and two partial areas of the second semiconductor pattern 128 respectively are covered by the second source 124 and the second drain 126. In addition, the first drain 116 is connected to the second source 124, and the first drain 116 and the second source 124 cooperatively form a rectangular electrode.
However, the overlapping area between the first source 114 and the first gate 112, as well as between the second drain 126 and the second gate 122, may result in stray capacitance, and the stray capacitance may consequently lead the pixel structure to consume more power, so it is quite necessary to reduce the stray capacitance in the pixel structure. However, because the channel between the first source 114 and the first gate 112, as well as between the second source 124 and the second gate 122, has to be maintained at a proper width of W and a proper length of L, the areas of the first source 114, the first drain 116, the second source 124 and the second drain 126 cannot be effectively decreased without any limit. As a result, the overlapping area between the first source 114 and the first gate 112 and the overlapping area between the second source 124 and the second gate 122 cannot be effectively decreased, and thus the stray capacitance is still high.